The present invention relates to a manually operated dispensing device for use with a double cartridge for dispensing two-component chemical systems. More particularly, it relates to a device that comprises a double thrust ram with two thrust ram parts each having a toothed surface on which teeth are provided, wherein the width of the thrust ram parts are equal or nearly equal, or, alternatively one thrust part is wider than the other. The device further comprises a drive assembly acting on the double thrust ram, which is actuated by a trigger lever, the drive assembly including a drive member which has a toothed surface with teeth for acting on the teeth of the double thrust ram.
A related dispensing device is already known from EP-A-0,615,787 to the same Applicant. This device had certain advantages over the prior art known at that time in that it could be manufactured with lower cost parts, such as plastic materials, due to the simultaneous meshing of a plurality of teeth. However, it has now been found that this device may still be substantially improved. In particular jamming, which is caused in the guide members by having a linear engagement movement, is a problem when used during the application of high dispensing forces. In addition, high jamming or tilting moments are created in that the driving dog must be guided with respect to the housing by an additional slider whose connecting link is disposed in a disadvantageous manner below the center line of the reactive force, particularly when the supply cylinders of the cartridges have the same or only slightly different diameters. Also, the lateral force impact point of cartridges having different diameters, especially widely different cylinder diameters, is not appropriately located. This results in all cases in a substantial loss of mechanical efficiency.
Another dispensing device has become known from U.S. Pat. No. 5,314,092, wherein the thrust rams acting on supply cylinders having different diameters are not symmetrically disposed, but rather are offset to the side having the higher reactive forces. The driving arrangement, however, does not provide a compensating link.
The thrust ram of known devices of the prior art, if they are made of plastic material, have reinforcing webs on both surfaces. The webs of these known devices are disposed away from the edges, e.g. in the center of each thrust ram part, thus leaving only restricted placement for the teeth.